Apparatus for spinning yarn

ABSTRACT

r comprising a spinning rotor journaled in a bearing housing and enclosing a spinning chamber having a circumferential groove and a hollow shaft defining its axis of rotation, a feeding device arranged upstream from the spinning rotor for supplying individual fibers from a fiber web and means creating an electrostatic field through which said fibers pass to charge said fibers, said means for providing said electrostatic field being formed of a first electrode comprising said feeding device and a second electrode comprising at least a portion of said spinning rotor, and a source of high voltage, said feed means being arranged so that said charged fibers are impelled toward said spinning chamber in a direction parallel to the axis of rotation of said spinning rotor, electrically conductive means located within said spinning chamber and connected to said second electrode for electrically discharging said fibers and baffle means covering said spinning chamber to prevent rearward movement of said discharged fibers, said fibers being centrifugally deposited in said groove parallel with each other and subsequently spun within said chamber.

O 3 Unite States Patent [151 3,673,78 1 Breitenbach July 4, 1972 541 APPARATUS FOR SPINNING YARN [56] References Cited [72] Inventor: Karl-Heinz Breitenbach, Stuttgart-Bad UNITED STATES PATENTS cannstattge'many 3,367,099 2/1968 Kubovy et a1 ..57/5s.s9 [73] Assignee: SKF Kugellagerfabriken GmbH, Ernst- 3,411,284 1 H1963 COFbaZ et /36 X Sachs 5 S h i f n Germany 2,231,324 2/1941 Crompton, Jr ..19/144 2,711,626 6/1955 Oglesby, Jr. et a1. ..57/34 [22] Filed: April 27, 1970 1 pp No: 32,134 FOREIGN PATENTS OR APPLICATIONS 979,962 1/1965 Great Britain ..57/58.89

[ Foreign Application Priority Data Primary Examiner-Stanley N. Gilreath M 3 1969 G up Assistant Examiner-Wemer H. Schroeder ay ermany 19 22 743 l Attorney-Richard Low and Murray Schaffer [52] U.S.-Cl ..57/58.89 51 Int. Cl. ..DOlh 1 12 [57] ABSTRACT [58] Field ofSearch ..57/34,36,90,58.89,58.91, Yarn spinning apparatus comprising a spinning rotor and means for feeding fiber slivers thereto. An electrostatic field being impressed across the fed sliver preferably by employing the rotor and feed means as the respective electrodes 6 Claims, 1 Drawing Figure PATENTEDJUL" 4 m2 3,678,781

IN VEN TOR.

KARL H n/z BRBWMH APPARATUS FOR SPINNING YARN The present invention relates to apparatus for spinning yarn from sliver fibers and in particular to a rotating spinning unit therefor.

Conventional spinning units include a spinning rotor journaled in a bearing housing and equipped with a spinning chamber, feed apparatus and a separating device arranged prior to the rotor with the aid of which the supplied fiber web is capable of being slivered into individual fibers which may be fed to the spinning chamber.

When using such spinning units it has been found that the strength of the resultant yarn depends substantially upon the manner by which the separated staple fibers are juxtaposed in the collecting groove or trough of the spinning rotor. It has been found, that optimum results are achieved when the individual fibers are aligned in parallel in the spinning rotor.

A stream of air (generally created by a negative pressure resulting from the rotation of the unit) is used as a conveying medium for the separated staple fibers in spinning units of the above described type. By means of such a stream the staple fibers are stretched as they are released from the separating unit in the direction of conveying. Because of the high speed rotary drive of the spinning rotors the fibers themselves are conveyed at very high speeds, producing disadvantageous results because of the increasing friction of the air against the inner wall of the guide channel. As a result substantial speed differences between the air molecules and the fibers are produced, particularly when the fibers are in contact with the boundary layer of air extending along the wall of the channel. The fibers become strongly curved and arranged in the air stream in such a manner that they enter the spinning chamber in a largely random orientation.

Because of the great centrifugal force created the rotor is effective in only spinning yarns of low strength. The random juxtaposition of the staple fibers is even more pronounced with rotors which simultaneously constitute the blower for producing the air stream required for conveying the fibers and for producing a negative pressure in the spinning chamber. Inherently there is produced vortexes are produced in the spinning chamber which have deleterious effect on the strength of the yarn and also on the lengths of yarn that can be produced in a given unit time.

[t is the present object of the invention to eliminate the aforedescribed shortcomings and difficulties in spinning units of the described type and to provide apparatus of simple construction and use which provides improved yarns at higher yields and with greater efficiency.

The present invention is based on the findings that the desired parallel juxtaposition of the staple fibers in the spinning rotor can be obtained to a high degree only when the fiber movement from the feeding device to the spinning rotor occurs substantially without the action of a moving carrying air stream. Therefore, the present invention provides the separating device with an electrostatic field created by a pair of electrodes one of which is formed by the feeding device and the other of which is formed by at least a portion of the inner surface of the spinning rotor.

In this connection it is to be noted that it is known to feed staple fibers to a spinning rotor by means of an electrostatic field. However, in these known devices the spinning rotor is not equipped with a spinning chamber adapted to double the A rotationally symmetrical spinning rotor 10 is employed, I

being of the general construction form and function described and illustrated in the copending applications of G. Bartling,

U.S. Pat. Ser. No. 32,133 filed Apr. 27, 1970 corresponding to German application No. P 19 22 742.0 and U.S. Pat. Ser. No. 32,205 filed Apr. 27, 1970 corresponding to German application No. P 19 22 876.3 which disclosures are incorporated herein by reference.

The rotor 10 has a spinning chamber 12 which is accessible from the right side of the rotor as seen in the drawing. The rotor 10 has a collecting groove or trough 14 provided at the circumference of the spinning chamber and is secured about a hollow shaft 16. The rotor is made of an electrically non-conductive material such as plastic and therefor has very small weight. The frontal and circumferential surfaces of the spinning chamber 12 are covered with a layer of electrically conducting material 18 connected with the shaft 16. The plastic of the spinning rotor is preferably of the family of ABS polymers, and the conductive layer may be for example, a copper nickel layer deposited thereon from the vapor phase.

The entrance of spinning chamber 12 is covered by means of a baffle plate 20 arranged coaxially to the spinning rotor and fixedly fastened to suitable housing 22. A guide tube 24 is fastened to the periphery of the bafile plate and tapers narrowing in the direction of staple movement. A feeding device 26 is arranged upstream from the guide tube 24 and is schematically shown only by a pair of rollers. The hollow shaft 16 and the feeding device are connected with a high voltage source 32 by electricalconductors 28, 33 which provide several thousand volts of tension. Preferably in the range of 20 to 30 thousand volts.

A fiber sliver web tape band 34 is supplied to the feeding device and is prestretched in the feeding device is a known manner. As is evident from the drawing that the plane in which the discharge of the feeding device is located is radially spaced from the axis of the rotor. Because the spinning rotor and the feeding device constitute respective electrodes and therefore produce an electrostatic field therebetween, individual fibers 36 withdrawn from the prestretched fiber web sliver tape at the exit of the feeding device, are attracted stretched or elongated and are then axially fed to the spinning chamber 12 through the tube 24 at high speed. When entering the spinning chamber the fibers are entrained by the low air pressure or vacuum created by the spinning chamber, and are moved transversely to the initial direction of feed to be deposited in the collecting groove 14. The fibers are deposited parallel to each other under the action of the centrifugal forces created by the rotor.

The fibers are withdrawn in the known manner from the groove 14 through the shaft 16. During such withdrawal the individual fibers are spun into yarn by the rotation of the fiber which forms a spiral balloon in the interior of the rotor.

When the individual staple fibers enter the spinning chamber and make contact with the conductive layer 18 their charge is neutralized. The electrode formed by the feeding device now exerts a reverse pulling force on the fiber and it is possible that individual staple fibers, particularly those still located in the immediate area of the rotor circumference may thereby be caused to fly outward in the reverse direction toward the feeding device 26. To prevent this the baffle plate 20 is, dimensioned and formed so that it is hit by the staple fibers, deflecting the same inwardly in the direction of the circumference of the spinning chamber.

The electrostatic force not only transports the fibers in a uniform manner from the feed device, it avoids turbulence along the conveying path, and offers the additional advantage in simultaneously separating the fibers as they leave the feeding device. This separation is caused partly by the high electrostatic field which withdraws the individual fibers from the predrawn fiber band or tape at the exit of the feeding device and partly by the fact that released individual fibers have the same electric charge whereby creating repelling forces which are effective to hold the fibers radially spaced from each other. The invention therefore makes it possible to avoid entirely the use of a mechanical separating apparatus.

Moreover the electrostatic field causes inherent stretching of the fibers asthey are discharged from the feeding device and an alignment of the fibers in a manner that they fly towards the spinning rotor in parallel to each other. The staple fibers thus flying towards the spinning chamber in a stretched condition. Once the fibers reach the spinning chamber they are entrained in the direction of movement of the spinning rotor under the action of the low pressure air or vacuum created by the spinning chamber and are independent of the electrostatic field. The axially moving fibers are displaced in a radial direction toward rotor trough by the centrifugal force which acts upon them. In this manner substantially all staple fibers are deposited parallel to each other.

The invention achieves a high uniformity in the yarn together with a substantial increase in the yarns strength because of the more favorably occurring doubling of the staple fibers and also achieves a substantial increase in the production rate.

Separating and feed mechanism of a type suitable for use with the present invention is shown and described in the copending U.S. Pat. application of G. Bartling Ser. No. 32,205 filed Apr. 27, 1970 corresponding to German application No. P 19 22 876.3, the details of which are incorporated herein. The feeding device can be equipped with one or several feeding rollers and if a single feeding roller is employed it may cooperate with a shoe or a second roller. In any event at least a portion of the feeding device must be electrically conductive to be adaptable for use as an electrode and may be preferably metallic, thearrangement being preferably suchthat the feeding device is capable of being connected with one pole of a source high tension v'o1tage.'The, at least single roller which is used in the feeding device need not itself consist of electrically conductive material and the same holds for a separating roller which, if used, may'be combined therewith. Particularly advantageous conditions, as to the movement of the fibers from the feeding device to the spinning rotor, are obtained when the discharge end of the feeding device is substantially coaxial to the spinning rotors so that the flight of the fibers occurs in an area of the electrostatic field in which forces are equal so that deflection of staple fibers cannot occur. The discharge end of the feeding device may also be provided at a predetermined distance from the axis of the spinning rotor, however, in this event it is advantageous to provide a stationary guide between the discharge end of the feeding device and the spinning rotor in order to guide the separated staple fibers toward the spinning rotor because in this event the transport of the fibers does not occur in a balanced field or forces and it may therefore occur that a staple fibers are deflected from the path of transport. The guiding device preferably comprises a tube of insulating material such as glass which may taper conically in the direction of fiber movement.

In order to counteract the tendency of the electrically discharged staple fibers which havetouched the wall of the staple fibers to be deflected radially to the inner circumference of the spinning rotor. Preferably the baffle plate always to be provided regardless whether the feeding device is coaxial to the spinning rotor or eccentric. In the first case a tube is employed for guiding the staple fibers and centrally passes through the baffle plate whereas in the latter case the tube may be arranged, for example, at the periphery of the bafl'le plate.

The spinning rotor itself may be an integral body of electrically conducting metal particularly steel. However, in order to limit the electrostatic field essentially to the spinning chamber. and to make the moving masses of the spinning rotor as small as possible, it is preferred to make the body of the spinning rotor of an insulating material equip it on its inner surface with an electrically conductive layer which may, for example, en-' tirel cover the inner wall of the rotor.

at is claimed is:

-1.-Apparatus for spinning textile fiber comprising a spinning rotor joumaled in a bearing housing and enclosing a spinning chamber having a circumferential groove and a hollow shaft defining its axis of rotation, a feeding device arranged upstream from the spinning rotor for supplying individual fibers from a fiber web and means creating an electrostatic field through which said fibers pass to charge said fibers, said means for providing said electrostatic field being formed of a first electrode comprising said feeding device and a second electrode comprising at least a portion of said-spinning rotor, and a source of high voltage, said feed means being arranged so that said charged fibers are impelled toward said spinning chamber in a direction parallel to the axis of rotation of said spinning rotor, electrically conductive means located within said spinning chamber and connected to said second electrode for electrically discharging'said fibers and baffle means covering said spinning chamber to prevent rearward movement of said discharged fibers, said fibers being centrifugally deposited in said groove parallel with each other and subsequently spun within said chamber.

2. The apparatus according to claim 1 wherein the feeding unit includes a discharge portion arranged at a distance from the axis of the spinning rotor and a stationary guiding device arranged between the discharge of the feeding device and the spinning rotor, for guiding the'fibers to the spinning rotor.

3. The apparatus according to claim 2 wherein the guiding device comprises a conically tapered tube of insulating material narrowing the direction of movement of the fibers.

4. The apparatus according to claim 3 wherein a baffle plate is arranged coaxially to the spinning rotor, said baffle plate covering said spinning chamber in an outward direction and consisting of insulating material, said guiding tube penetrating through said baffle plate.

5. The apparatus according to claim 1 wherein the spinning rotor is made of insulating material and has an electrically conducting layer on its inner surface, the conducting layer covering the entire inner face of said rotor.

6. The apparatus according to claim 1 in that said feeding device is equipped with at least one roller and with a cooperating counter-piece. 

2. The apparatus according to claim 1 wherein the feeding unit includes a discharge portion arranged at a distance from the axis of the spinning rotor and a stationary guiding device arranged between the discharge of the feeding device and the spinning rotor, for guiding the fibers to the spinning rotor.
 3. The apparatus according to claim 2 wherein the guiding device comprises a conically tapered tube of insulating material narrowing the direction of movement of the fibers.
 4. The apparatus according to claim 3 wherein a baffle plate is arranged coaxially to the spinning rotor, said baffle plate covering said spinning chamber in an outward direction and consisting of insulating material, said guiding tube penetrating through said baffle plate.
 5. The apparatus according to claim 1 wherein the spinning rotor is made of insulating material and has an electrically conducting layer on its inner surface, the conducting layer covering the entire inner face of said rotor.
 6. The appAratus according to claim 1 in that said feeding device is equipped with at least one roller and with a cooperating counter-piece. 